A herd of deer in their summer coats.Ernst Haas / Getty
This story was originally published by Hakai Magazine and is reproduced here as part of the Climate Desk collaboration.
Clear blue sky above a forested island surrounded by glittering sea. Wild. Uninhabited. Protected. It appears as if we’re approaching paradise. We cut the boat’s engine and nose into a rocky beach.
Crowned with Douglas fir, Garry oak, and arbutus trees, D’Arcy is one of 600 islands and islets scattered between mainland Washington State and British Columbia’s Vancouver Island. An invisible border divides the islands into the San Juan (US) and Gulf Islands (Canada) archipelagos. Prior to colonization, Indigenous people hunted, foraged, and gardened here as they did on islands throughout the Salish Sea. Then, between 1891 and 1924, the government of the day sent lepers here—mostly men of Chinese descent—and essentially left them to die. Now within Canada’s Gulf Islands National Park Reserve, D’Arcy is part of a groundbreaking study about imperiled island ecosystems and climate change.
Tara Martin, the project’s lead, is a professor in the Department of Forest and Conservation Sciences and Liber Ero Chair in Conservation at the University of British Columbia. She has brought her team of grad students here on this spring day to collect evidence of what she calls the “greatest environmental tragedy” facing these islands. It’s part of a problem that has become common in North America and around the world—a problem with clear causes and what at first appear to be achievable solutions.
If only it were that easy.
Once everyone is safely ashore, Martin bounds ahead. Her enthusiasm is infectious. As her students fan out at the forest’s edge, she traces a path through trees that seem, to the untrained eye, to be thriving. But to Martin, they are a stand of “the living dead.” To glimpse this forest’s future, she advises me to ignore the green canopy six stories above and look down around my feet. The understory should be thick with flowering plants and shrubs. Instead, it’s mostly brown and spacious. “If there were no deer here,” she says, “it would be green all the way down to the bottom.”
Columbian black-tailed deer range from southern British Columbia to Southern California, and as far east as the Cascade Range and southern Sierra Nevada. They are native to this archipelago. They are also wildly out of balance. By the late 1800s, foreign settlers had exterminated the islands’ cougars and wolves, the deer’s primary predators, and alienated Indigenous people from their traditional deer hunting grounds. Over the past century, wildlife managers here and across the continent encouraged the proliferation of all deer species—popular game animals. More recently, changes in regulations and cultural attitudes have resulted in a dramatic drop in hunting. Deer have never had it so easy. Martin estimates that their population on the islands is now 10 times what it was before colonists arrived.
Here and there, oceanspray shoots up like topiary umbrellas. Indigenous people used these flowering shrubs, also known as ironwood, for making tools and utensils. Well past two meters tall, these specimens are old-timers, Martin explains, up to 100 years in age, that have been relentlessly clipped and shaped by deer who swim between islands. Few, if any, new oceanspray plants survive because deer eat them before they can establish.
It’s the same for other bushes and flowering plants. Seedling and sapling trees often meet a similar fate. Native deer prefer to browse native fare, especially succulent flowering plants, giving unpalatable invasive plant species an edge. Gone too are the native, perennial, tussock-forming grasses that some birds favor for nesting. What the deer leave behind is an impoverished understory dotted with moss and thorny Himalayan blackberry. And the evidence of deer overbrowsing reaches well beyond the trees.
Martin leads me to a meadow near the beach where the sun illuminates a grassy field of vibrant green. While I take in the inviting scene, she conjures a vanished world of purples and pinks, the trill and hum of pollinating birds and bees—the way this meadow used to be. Martin grew up just 22 kilometers north of here, on Saltspring Island, in the 1970s. “There were places you could be knee-deep in wildflowers,” she recalls. Now, with the proliferation of deer, development, and other stressors, “those places are long gone.” They’ve been replaced by a carpet of invasives, including European orchard grass. It’s a process repeated throughout the archipelago, she says, and wherever overabundant deer are found.
I scan the field and the surrounding forest but cannot spot the accused. It’s as if they heard us coming and swam away.
Deer have been on human minds and in human lives for eons. Between 120,000 and 108,000 years ago, Homo erectus relied on deer for food on the island of Java. A Neanderthal living in what is now Germany carved chevron shapes into a deer bone 51,000 years ago. Between 33,000 and 30,000 years ago, Paleolithic people painted on the walls of Chauvet Cave in what is now France. Among the animals they left for us to ponder are red deer, reindeer, and Megaloceros—the largest deer to have ever lived.
Deer have appeared in the art and mythology of the ancient Egyptians, Greeks, Celts, Hindus, and Chinese, for whom deer represent longevity and prosperity. They are prominently represented in medieval European heraldry, mythology, and culture. The deer is a sacred symbol of the Maya world and its image appears throughout their culture. Maya mythology holds that it was a stag, using his hoof, who formed the sexual organs of the moon. The Maya sacrificed deer to their gods and used deerskin to record the pre-Columbian Maya codices. To this day, many Maya people have the surname Ceh, which means “deer” in the Mayan language.
Across cultures and time, people have revered deer as symbols of spiritual authority. A deer’s antlers, resembling a crown, extend beyond its head and body, connecting it to the heavens. Those same antlers drop off and regrow each year, making them symbols of regeneration. In Christian iconography, the stag serves as a symbol for Christ, conveying piety, devotion, and God’s care for his children. Deer star in countless folk tales and fables. In 1942, Walt Disney Studios released the animated film Bambi, which has helped shape North American perceptions of deer ever since. Through it all, human hunters have prized deer for their meat.
Deer are special. We are not talking about a plague of locusts, rats, or venomous snakes—we’re talking about deer. And whenever the words deer and problem come together, many people have big feelings.
Both Indigenous knowledge and Western science have long recognized that deer can have big impacts wherever their predators are few, causing a trophic cascade—the ecological term for changes throughout a food web. Aldo Leopold, the first professor of game management in the United States, famously observed a century ago how overabundant deer on Arizona’s Kaibab Plateau degraded the habitat to the extent that their population collapsed. “I now suspect,” he wrote in his seminal A Sand County Almanac, “that just as a deer herd lives in mortal fear of its wolves, so does a mountain live in mortal fear of its deer. And perhaps with better cause, for while a buck pulled down by wolves can be replaced in two or three years, a range pulled down by too many deer may fail of replacement in as many decades.”
Tara Martin has been studying the effects of overabundant deer for more than 15 years. Because some islands in the Salish Sea have deer and some don’t, they provide a natural experimental setup to measure deer’s effect on the environment. Martin has found that palatable plant species cover, richness, and diversity are 92 percent lower where deer are common and 52 percent lower where deer are scarce (less than 0.08 per hectare) compared with areas with no deer at all. On some islands, native black-tailed deer and exotic fallow deer occur at densities of over 20 per square kilometer. The resulting loss of understory means the loss of habitat for numerous bird species, which rely on the first 1.5 meters above the forest floor for cover, nesting sites, and food such as flowers and seeds.
“There are over 300 species in this ecosystem that are being negatively impacted by overbrowsing,” Martin says. “Many of those are plants, but it also includes bumblebees and songbirds, and our amazing alligator lizard and sharptailed snake species that are at risk of [local] extinction.”
While her work has helped establish that overabundant deer are threatening the local ecosystem, she suspects the effects could also reach beyond this place. Here on D’Arcy Island, she and her team have set up soil moisture meters and camera traps to gather evidence that overabundant deer may make forests drier. Drier forests are more likely to burn frequently and intensely, releasing carbon into the atmosphere and contributing to global climate change.
While Columbian black-tailed deer, a type of mule deer, are surging on parts of North America’s West Coast, some other populations of mule deer, including those in Colorado and Wyoming, aren’t faring as well and have declined. White-tailed deer are also experiencing some regional declines—including in New Brunswick and Georgia. In general, though, they’re booming. The oldest surviving deer species, whitetails have ranged across the continent since the last ice age. During the 1800s, their population crashed due to overhunting and habitat loss, reaching just 500,000 in 1900. But today, white-tailed deer are the most widely distributed and numerous large wild animals in North America. In the United States alone, there are over 30 million white-tailed deer—about one for every 11 people.
In the forests of Wisconsin and Michigan, research suggests, expanding whitetail populations are responsible for at least 40 percent of the change observed in forest structure. “It’s rare in ecology to find one factor that accounts for so much change,” says Donald Waller, a retired professor of botany at the University of Wisconsin–Madison, who has studied white-tailed deer for over 20 years. His findings mirror Tara Martin’s on D’Arcy Island. Waller reports that white-tailed deer occur at “chronically high densities” not just in the Midwest, but throughout most of eastern, southern, and central North America. But mounting evidence about how they damage ecosystems isn’t getting through, Waller says: It “has yet to convincingly sway public opinion or wildlife policies in many regions.” Managers, decision-makers, and the general public still often dismiss news of habitat destruction and wildflower losses as “isolated or anecdotal.”
Wildlife agencies in North America still rely largely on hunting licenses for revenue. But as fewer young people are taking up hunting, and hunting becomes less popular in many regions, that model is becoming unsustainable—both as a revenue generator, and for deer numbers in areas where wild predators haven’t recovered.
North America is not alone in facing the challenges posed by overabundant deer. It’s a similar story in the United Kingdom, Finland, and Japan.
Despite the damage done, deer are just being deer. Humans have reduced or eliminated vast tracts of wilderness and have mined, plowed, logged, drilled, paved, and drained deer’s natural habitat while growing enticing farms, yards, and gardens in predator- and hunter-free urban and suburban environments. We created this problem by reordering the world in ways that encourage deer to become hyperabundant within much more constrained landscapes. What are we prepared to do to solve it?
“I think there’s a blind spot,” Tara Martin says. “People don’t want to know and we don’t want to face it.” And our governments try and look the other way. “They pretty much tell me point blank that they do not want to attract controversy. They just don’t want the hate mail.”
Nearly 4,000 kilometers east of uninhabited D’Arcy, residents of another island find themselves caught in that dilemma. On Staten Island, New York City’s “forgotten borough,” white-tailed deer overrun neighborhoods and city streets and provide a vector for Lyme disease. Vehicle collisions with deer are common, costly, and deadly. While there is broad agreement that the ballooning deer population causes problems, what to do about it has long been such a flashpoint that the media often calls it the “Deer Wars.”
Reporters construct narratives that pit whitetails against people, people against people, and deer against the environment. On one side of the divide are those portrayed as hands-off “animal lovers” who want to let nature take its course; on the other are those who would prefer to see the “rats with hooves” sleep with the fishes.
While debate raged, consequences multiplied. According to Cliff Hagen, president of the local conservation group Protectors of Pine Oak Woods, the island probably hadn’t had a viable deer population for centuries because of farming, development, and overhunting. But as policies designed to recover deer populations succeeded on the mainland, deer started to arrive on Staten Island in the 1990s where they proceeded to proliferate and “decimate” what was left of the native flora, including endangered Nantucket juneberry and locally rare Torrey’s mountain mint.
At the same time, the deer encouraged the spread of invasive plants such as stilt grass, garlic mustard, and mile-a-minute, a fast-growing vine native to India and East Asia. These invasives change the chemical composition of the soil and prevent native plants from growing back. Clay Pit Ponds State Park, a 103-hectare nature preserve encompassing wetlands, ponds, sand barrens, spring-fed streams, and woodlands, is now carpeted with invasive grasses because of these changes, says Hagen. “Many of the trees are still there. But once those trees fall, there are few, if any, saplings growing. So the future of the forest does not look good.”
For Hagen, any discussion about protecting wildlife must also consider the health of the ecosystem upon which wildlife depends. On top of that, wherever elected officials and wildlife managers face an overabundance of deer, they must also weigh varied and often competing values and perspectives, such as public safety and the expectations of hunters, animal rights activists, landowners, commuters, and residents of urban and rural communities—not to mention the lives of deer and other affected native species. Then, decision-makers face the unenviable task of choosing an ethical, practical, and affordable way forward.
One of the most ecologically sound approaches, depending on the available habitat, is to reintroduce or support the recovery of native predator populations. But where that’s practically or politically impossible, the options on the table are traditional hunting, culling by sharpshooters, and fertility control. In a 2020 paper, Texas A&M University environmental ethicist Clare Palmer and coauthors suggest that the last of these might be best “in terms of deer welfare,” but “in terms of naturalness, lethal control may have the edge,” because it’s similar to predation. Limited resources might also tip the scales toward lethal control, because it’s cheaper and logistically simpler. But, Palmer and the others write, “there is no simple or single answer as to what constitutes ‘ethical management.’”
One thing is clear: it’s unethical to do nothing. “If you’re worried about ecosystems,” Palmer says, “it seems like that’s a reason to reduce the deer population. If you’re worried about human welfare, given the ways we live, it seems like that’s a reason to reduce the deer population. If you’re worried about animal welfare, it seems like that’s a reason to reduce the deer population.”
“Traditionally, conservation, and preservation has been all about not intervening,” she concludes. But with the additional pressures of climate change, “interventionist conservation seems much more pressing.”
On Staten Island, a borough of half a million people, city officials ultimately chose a vasectomy program. They felt it would be more humane and less controversial than killing deer through an organized cull, and it was cheaper than ovariectomies. By 2020’s close, a team of veterinarians had sterilized 93 percent of the estimated 1,719 male deer on Staten Island, at a cost of $6.6 million. As white-tailed deer have an average lifespan of 10 years, it will take at least a decade to gauge the effects. Still, over a four year period, the deer population dropped from 2,053 to 1,555, and both vehicle collisions and Lyme disease infections declined.
In the end, such choices are often more political than ethical. James Oddo, past president of Staten Island Borough, initially supported a cull, but got behind the vasectomy option because it “was the path of least resistance,” he told the Staten Island Advance. “Proponents will argue it was the only way to do something sooner rather than later because we knew a cull would eventually involve litigation. The money that was spent gave the city the plausible deniability to say we did something.”
Back in British Columbia, six kilometers north of D’Arcy Island, I wade after Tara Martin through understory thick and green. We’re traversing another small island in the Salish Sea, beneath a similar canopy of oak and fir, but here a profusion of herbs and plump oceanspray—along with seedlings, saplings, and adolescent trees—rises all around us. Unlike the stand of the living dead on D’Arcy Island, this small, fully functioning forest has a brighter future in store.
There’s a certain swagger in Martin’s step as she shows off the place. Uninhabited SISȻENEM (cease-kwa-nem) Island is one of the few islands in her study area that doesn’t have deer, due to swift local currents. Thanks in part to her work behind the scenes, the Land Conservancy of British Columbia, a nonprofit, charitable trust, purchased the island from a private seller in 2021 and is in the process of transferring it back to the local W̱SÁNEĆ [wh-say-nech) First Nations. A loose translation of W̱SÁNEĆ means “sitting out for pleasure of the weather.” The island is, Martin says, one of the last examples of what this coast once looked like and could resemble again.
And now she picks up the pace. It’s clear she’s saved the best for last. She leads me from the cool, green shadows into a floral fireworks display that runs the gamut from snow white to butter yellow, hot pink to pale lilac, and violet to cobalt blue. Below the flicker of butterflies and the hum of countless bees is a wonderland thicket of flowering plants with some individuals over 100 years old and over a meter high.
